1 3 5-haloxylene extraction

ABSTRACT

SELECTIVE EXTRACTION OF 1,3,5-CHLOROXYLENE FROM OTHER CHLOROXYLENE ISOMERS INITIALLY PRESENT IN A HETEROGENEOUS MIXTURE COMPRISING AN HF LAYER RELATIVELY RICH IN 1,3,5CHLOROXYLENE AND A CONTACTING ORGANIC LAYER RELATIVELY POOR IN 1,3,5-CHLOROXYLENE IS EFECTED BY HEATING THE HETEROGENEOUS MIXTURE TO A SUFFICIENTLY HIGH TEMPERATURE TO ENSURE THAT THE HF LAYER IS UPPERMOST IN THE EXTRACTION VESSEL. IN A PREFERRED EMBODIMENT, THE EXTRACTION IS CONDUCTED IN THE ABSENCE OF A DILUENT.

United States Patent Oflice 3,641,168 Patented Feb. 8, 1972 3,641,168 1,3,5-HALOXYLENE EXTRACTION John D. Bacha, Monroeville, and Charles M. Selwitz,

Pitcairn, Pa., assignors to Gulf Research & Development Company, Pittsburgh, Pa.

No Drawing. Continuation-impart of application Ser. No. 785,798, Dec. 20, 1968. This application Dec. 3, 1969, Ser. No. 881,851

Int. Cl. C07c 25/04 U.S. Cl. 260650 R 4 Claims ABSTRACT OF THE DISCLOSURE Selective extraction of 1,3,5-chloroxylene from other chloroxylene isomers initially present in a heterogeneous mixture comprising an HF layer relatively rich in 1,3,5- chloroxylene and a contacting organic layer relatively poor in 1,3,5-chloroxylene is effected by heating the heterogeneous mixture to a sufficiently high temperature to ensure that the HF layer is uppermost in the extraction vessel.

In a preferred embodiment, the extraction is conducted in the absence of a diluent.

This application is a continuation-in-part of Ser. No. 785,798, filed on Dec. 20, 1968, now U.S. Pat. No. 3,577,- 470, which issued May 4, 1971.

This invention relates to a method of separating meta orientated haloalkyl benzenes from isomeric mixtures thereof and, more particularly to a method of separating 1,3,5-chloroxylene from a mixture of its six possible isomers.

Haloxylenes can exist in six isomeric forms, but of these the 1,3,5-haloxylene,

wherein X is halogen, has an appreciable commercial attraction. For example, as shown in U.S. Pat. No. 3,352,- 927 to De Vries et al., 3,5-xylenol can be used in the preparation of a readily curable extremely attractive formaldehyde-type thermosetting polymer. The 3,5-xylenol required for such polymer can easily be obtained by conventional hydrolysis of 1,3,5-chloroxylene.

As disclosed in our copending application, Ser. No. 785,798, we have found that haloxylenes which do not fit the definition of 1,3,5-haloxylene can be effectively isomerized to 1,3,5-haloxylene by the mere expedient of contacting the same with HF and BF preferably in the presence of an orthohalotoluene. By haloxylenes we intend to include chloro-, bromo-, fluoroand iodoxylenes, although the procedure is particularly pertinent to the isomerization of chloroxylenes.

The isomerization reaction defined in said copending application is effectively carried out merely by bringing the haloxylene charge (which can include any one or any combination of non-1,3,5-haloxylenes) in effective contact with HF and BF Thus, in a preferred embodiment anhydrous HF is added to a closed reactor containing the haloxylene charge, after which BF gas is added thereto. The molar ratio of HF to BF, used in the isomerization reaction can be from about 100:1 to about 1:1, preferably from about 10:1 to about 2:1. The molar ratio of HF and BF;.; (as a combined entity) to the haloxylene charge can be from about 300:1 to about 1:1, preferably in the range of about 50:1 to about 5:1. The contents of the reactor are stirred during the course of the reaction,

with the temperature being as low as about 25 C. or as high as about 160 C., but preferably remaining in the range of about 55 to about C. Below about 25 C. the reaction rate is too slow, whereas at temperatures in excess of about C. dehalogenation and the formation of decomposition products and polymers is facilitated. Pressure is not critical and can be as low as about 15 pounds per square inch gauge to as high as about 1200 pounds per square inch guage, or even higher, but preferably is maintained within a range of about 100 to about 800 pounds per square inch gauge. In effect any pressure sufiicient to maintain the HP in the liquid phase can be employed. The reaction time is highly dependent upon the other factors discussed herein and can therefore be varied over a wide range, although, in general, a time of about one minute to about five hours, preferably about 15 minutes to about one hour can be used.

At the end of the reaction period stirring is terminated and a heterogeneous system having three phases is found. As will be discussed in greater detail hereinbelow, the relative positions of the three phases are dependent upon the composition of the charge to the reactor and upon the temperature at which the three phases are maintained. However, when the three phases are maintained at a preferred temperature, e.g., between about 55 to about 95 C., the lower phase is a liquid containing a mixture of haloxylenes (initial isomers and isomers formed during the process) and the disproportionation products, such as halotoluenes and halotrimethylbenzenes. The intermediate layer is also a liquid and consists essentially of HF, BF and a mixture of haloxylenes. From about 50 to about 90 percent by weight of the intermediate layer is comprised of a complex of HF, BF, and the desired 1,3,5- haloxylene isomer, with the remainder made up of any one or combination of other haloxylene isomers and disproportionation products thereof complexed with HF asd BF The upper phase is gaseous and under the conditions of the reaction defined herein is composed almost wholly of BF Hereinafter, the three phases will be referred to as the organic or chloroaromatic layer, the HF layer, and the BF phase, respectively. The intermediate liquid phase, i.e., the HF layer, is withdrawn from the reaction zone and the components therein separated by any suitable procedure such as the following. The HF layer so removed is subjected to distillation under any suitable conditions, for example, a pressure of about five to about 800 pounds per square inch gauge, at a temperature of about 0 to about 180 C. The complex is thus broken and gaseous HF and BE, is removed overhead. The remaining product can then be further purified to remove any disproportionation products and some of the undesired haloxylene isomers thereof, for example, by distillation, and thereby leave behind the desired 1,3,5-haloxylene or a mixture rich in 1,3,5-haloxylene, which can be converted, as noted, by hydrolysis, for example, to 3,5-xylenol.

Although the above procedure is effective to convert, by isomerization, the haloxylene charge to the desired isomer, 1,3,5-haloxylene, there is also a tendency under certain conditions, for example, at elevated temperatures, for disproportionation to the halotoluenes and halotrimethyl benzenes. This means the loss of two molecules of the haloxylene charge toundesired compounds, and, to the extent this occurs, production of 1,3,5-ha1oxylene is thereby reduced. To the extent disproportionation is inhibited, the haloxylenes that are not converted to disproportionation products are thus available for isomerization to desired 1,3,5-xylene. By conducting the isomerization reaction in the added presence of a halotoluene there is about 70 to about 98 percent reduction in the amount of haloxylene converted to disproportionation products 080 82 H 0 8030 0 0582 0 3 00 80 8 0000 8 0032 8 00 0 80.82 0 6808882 00 0 E 880 80 0 5853 3880 $8 8 080 0. 0 0 80880 mm 8 0 8058 08 8080 NO 080 0 0 0 0 8050 0080 0 w H 40 B0 08 008 80 9 08 800808 0 08 35500308 "No $8 008 08 88-88 08 8 2 5 0 2 8 8 4 8. a

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As clearly illustrated in Table IV, the temperature at which the HF layer assumes the uppermost position in the reaction vessel is dependent upon the composition of the charge (Run Nos. 35-38). Thus, while the HF layer inversion takes place at about 17:3 C. (Run No. 35) when the molar ratios of chlorotoluene, HF and BF to chloroxylene are relatively high, inversion takes place at increasingly higher temperatures as these ratios decrease.

It is to be understood that the above-described embodiments are simply illustrative of the principles of the present invention and that various other modifications and changes may be devised by those skilled in the art which will embody the principles of the invention and fall within the spirit and scope thereof.

.We claim:

1. A process for extracting 1,3,5-chloroxylene from a mixture comprising liquid HF, BF and a chloroxylene charge comprising 1,3,5-chloroxylene and at least one other chloroxylene isomer and optionally chlorotoluene the molar ratio of HF to BF being from about 100:1 to abut 1:1 and the molar ratio of combined HF and BF to said chloroxylene charge from about 300:1 to about 1:1, which comprises maintaining said mixture at a temperature of about to about 150 C. and a pressure of about 15 to about 1200 pounds per square inch for about 0.1 to

about one hour, resulting in an upper liquid HF layer containing 1,3,5-chloroxylene, HF and BE, and a lower layer containing said other chloroxylene isomer, separating said two layers from each other and thereafter separating 1,3,5-chloroxylene from said upper layer.

2. The process of claim 1 wherein the molar ratio of HF to BF is from about 10:1 to about 2:1, the molar ratio of combined HF and BF to said chloroxylene charge is from about :1 to about 1:1, the temperature is from about 10 to about C., the pressure from about 100 to about 800 pounds per square inch.

3. The process of claim 1 wherein chlorotoluene is added to the mixture being treated in an amount so that the molar ratio of chlorotoluene to 1,3,5-chloroxylene and the isomers thereof is from about 0.5 :1 to about 10: 1.

4. The process of claim 2 wherein chlorotoluene is added to the mixture being treated in an amount so that the molar ratio of chlorotoluene to 1,3,5-chloroxylene and the isomers thereof is from about 2:1 to about 5:1.

References Cited UNITED STATES PATENTS 2,727,075 12/1955 Mattano 260650 R 2,819,321 l/1958 Pray 260650 R 2,881,224 4/1959 McCa-ulay et al. 260-650 R HOWARD T. MARS, Primary Examiner jgyggy UNITED STATES PATENT OFFICE CERTIFICATE @F QORRECTFQN PatmuzNo. 3,641,168 Datai I February a, 1972 InvaMmr(s) John D. Bacha and Charles M. Selwitz It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

- Column 3, Table I, last column of Run No. l,"6." should columns, Table I, last column of Run No. 2, "6.3" should be "6.1".

Column 3, Table I, last column of Run No. 3, "5.1" should be -l|5.4ll. Y I

I Column 3, Table I, last column of Run No. 4, "5.4" should Column 3, Table 1, last column of Run No. 5, "4.3" should Column 3, Table I, Run No. 9,under the.heading "l,2,5", "26.6" vshould be "26.9".

Column 3, Table I, last column of Run No. 8, "2.1" should be "2.7".

Column 3, Table I, last column of Run No. 9, 6.7" should be "6.2".

Column 3, Table I, last column of Run No. 10, "5.2" should be "5.5".

Column 3, Table I, last column of Run No. 11, "5.5" should be "5.8". v 7

Column 3, Table.I, Footnote 4 should read "o/m/pz63/3o/7".

Column 6, Table III, last column of Run No. 27, ".3" shouldv be "8'3" I 4 Sheet 1 of 2 v UNITED STATES PATENT OFFICE CERTIFICATE 0F CO RECTION Patent No. 1, 168 Dated February 8, 1972 lnventoflss John D. Bacha and Charles M. S'elwitz It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 7, Run No. 35, under the heading "126-", '14. 3 should be "15. 3

Column 9, line 24, after "charge" please inser't "being".

Sheet 2 of 2 Signed and sealed this 20th day of June I972.

(SEAL) Attest:

' EDWARD M'.FLETCHER, JR. ROBERT GOTTSCHALK Com issioner of Patents Attesting Officer 

